Field
The present application relates to an endoscope, such as an endoscope having a lateral direction of view, comprising an endoscope shaft, which has an outer tube and an inner tube, which is surrounded by the outer tube, wherein the outer tube is configured to accommodate and/or to operate a first optical assembly in the distal region of the endoscope shaft, and wherein the inner tube is configured to accommodate a second optical assembly in the distal region of the endoscope shaft, wherein the inner tube and the outer tube are mounted in such a way that the inner tube and the outer tube can be rotated in relation to each other, and wherein an axial bearing is arranged between the outer tube and the inner tube in the proximal region of the endoscope shaft, and wherein the axial bearing has an outer ring, which is associated with the outer tube, and an inner ring, which is associated with the inner tube.
Within the framework of the present disclosure, the term endoscope includes video endoscopes, i.e. endoscopes in connection with at least one image sensor, which can be configured to record a video recording, regardless of whether the image sensor is arranged distally in the endoscope shaft, proximally in a handle or externally in a camera head, which can be placed on an eyepiece in the proximal region of the endoscope, i.e. on the side of an operator.
The term “direction of view” (DOV) relates to the sideways and backwards view deviating from the longitudinal axis of the endoscope, which is represented as the polar angle, wherein an angle of view of 0° indicates a straight-ahead view in the longitudinal direction of the endoscope shaft, while for example, an angle of view of 90° indicates a direction of view deviating from the straight-ahead view at a right angle.
Prior Art
In the case of endoscopes, such as video endoscopes with a direction of view≠0°, it is necessary that two optical assemblies can be moved relative to each other rotationally in the distal optical system. For this, a radial and axial mounting of the optical assemblies is necessary. The radial mounting restricts the relative movement of the assemblies relative to each other in the radial direction; the axial mounting restricts the relative movement in the axial direction of the endoscope. In order to avoid negatively impacting the optical quality, it is also advantageous if the axial mounting is built without play in order to not change the optical path by an axial displacement of the optical assemblies relative to each other.
In the state of the art, the axial absence of play is created by the pretensioning of the mounting with a spring, for example a spiral spring, which is located in the handle region of the endoscope.
In the case of the video endoscope according to EP 1 787 570 B1, a radially acting mounting is located in the handle. Both a radial and an axial mounting are located between the two distal optical assemblies. Both the torque, as well as the axial force are transferred via two tubes, to each of which an optical assembly is connected. The distally arranged axial mounting is hereby held axially and without play by means of the spring placed in the handle region.
Through the spring placed in the handle for state-of-the-art endoscopes for pretensioning the axial mounting, axial forces must also be transferred in addition to the torque. The structure is hereby relatively complicated and complex.
Moreover, video endoscopes with a lateral direction of view, i.e. a direction of view not equal to 0°, are known, in which a distal deflection prism of a first optical group is accommodated by an outer tube and the image sensor unit of the second optical group, such as a CCD image sensor unit, is arranged in an inner tube. The two tubes for the optical assemblies are in this case tensioned by a spring in the proximal handle region, wherein a radial mounting is provided in the distal region of the endoscope shaft between the outer tube and the inner tube. The installation of the spring is very complex. Moreover, the mounting of the inner tube and of the outer tube is very rigid since the distance between the tubes is very small. Since the optical assemblies provided for the inner tube and the outer tube also have a small, radial separation distance, it can happen that this leads to a jam in the endoscope shaft in the distal region.
FIG. 1 shows schematically an endoscope 1 known from the state of the art. The endoscope 1 has on the proximal end shown on the right a handle 3, which opens into a shaft 2. The distal end of the shaft 2 is shown on the left side in FIG. 1.
The handle 3 has a rotary swivel 4, by means of which via bar magnets 5, which are connected with an inner tube 7, the inner tube 7 can be turned with respect to an outer tube 6 in order to change the direction of view of the endoscope 1. In the handle 3, the inner tube 7 is also mounted by means of a radial bearing 8. Moreover, the handle 3 comprises a pretensioning device comprising a compression spring 9, which is pretensioned with respect to a stop 10 for the compression spring 9. The compression spring 9 ensures that the inner tube 7 in the axial direction is pushed or respectively pretensioned towards the distal end 11 of the shaft 2.
On the distal end 11, the shaft 2 has a window 12, which looks sideways. An optical assembly 13 with lenses and prisms, with which the light entering through the window 12 is directed in a direction parallel to the longitudinal axis of the shaft 2, is located behind the window 12. The optical assembly 13 is held by a holder 14, which is connected with the outer tube 6. The window 12 is also part of the optical assembly 13.
A second optical assembly 16, which in this case ends in an image sensor unit 19, connects proximally to the first optical assembly 13. The second optical assembly 16 is mounted in a holder 17, which is connected with the inner tube 7 such that it performs rotations or displacements of the inner tube 7. The inner tube 7 is mounted radially with respect to the outer tube 6 in the region of the distal end 11 of the shaft 2 by means of a radial mounting 18.
The distal front surface of the holder 17 of the second optical assembly 16 and the proximal front surface of the holder 14 of the first optical assembly 13 are arranged opposite each other and form an axial bearing 15. Through the pretensioning of the inner tube 7 in the axial direction by the compression spring 9 in the handle 3, the axial bearing 15 is closed, i.e. the distal-side front surface of the holder 17 is pushed against the proximal-side front surface of the holder 14. The axial position of the second optical assembly 16 with respect to the first optical assembly 13 is thus set and an optimal optical quality is achieved.
Since the axially acting pretensioning force is conveyed via the longitudinally extending inner tube 7, any tilting, twisting or displacement of the inner tube 7 in the outer tube 6 leads to the axially acting pretensioning force not being optimally transferred to the axial bearing 15. This can lead to an impairment of the optical quality.